I. Field of the Invention
The present invention relates to fluid systems and, more particularly, to a positive displacement flow meter with means for indicating the rate of fluid flow through the system and which is particularly designed for fluids with a high solid content.
II. Description of the Prior Art
Previously known flow meters, such as that described in my previous U.S. Pat. No. 3,282,102, issued on Nov. 1, 1966, have enjoyed wide spread acceptance throughout the trade and have proven commercially successful. This type of flow meter generally comprises a vane mounted on a rotatable shaft which divides the flow meter inlet and outlet into two fluid chambers when there is no fluid flow through the flow meter. As fluids begin to flow through the flow meter, the vane rotates with the shaft and permits fluid communication between the flow meter inlet and the outlet. The rotational position of the vane is proportional to the fluid flow rate through the flow meter so that a pointer attached to one end of the shaft provides a visual indication of the flow rate exteriorly of the flow meter.
One limitation suffered by these previously known flow meters is that these flow meters tended to clog and malfunction when used with fluids with high solid content, commonly known as slurries. In particular the solid content of such slurries tended to accumulate between the flow meter shaft and the flow meter housing and thus impose an additional and unpredictable frictional load upon the flow meter shaft. This additional frictional load resulted in erractic flow meter readings which required disassembly of the flow meter for its repair and cleaning.